Question

A pencil partly immersed in water in a glass tumbler appears to be bent or broken because:

Answer 1

Obliquely incident light rays change their direction upon change of medium depending upon the density of the medium. Water is optically denser medium compared to air. The light from the part of the pencil which is immersed in water, travels from water to air i.e, denser medium to rarer medium. Therefore, it light bends away from the normal. Because of this bend, the pencil appears to be bent or broken.